aitools: add --param flag for parameterized SQL queries

[simonfaltum]

Why

The Databricks SQL Statement Execution API supports named parameters (:name markers in SQL plus a parameters payload), but the experimental aitools query and statement submit commands never set that field. Users who want to avoid SQL injection, sidestep shell-quoting issues with dates and strings, or run typed bindings (DATE, INT, DECIMAL(...), etc.) currently have to drop down to raw HTTP. This wires the field through.

Changes

Before: no way to pass parameters. SQL had to inline every value as a literal, with all the quoting and injection risk that implies.

Now: --param is a repeatable flag on query, statement submit, and the multi-query batch path. Format:

• --param name=value (default type, server-side STRING)
• --param name:TYPE=value for typed bindings, e.g. --param since:DATE=2026-01-01

Empty value (--param opt=) is sent as NULL via omitempty. Duplicate names and missing = are rejected at flag-parse time. In batch mode the same parameter set is applied to every statement.

Implementation:

• New parseParams helper in experimental/aitools/cmd/params.go, plus parser unit tests.
• Plumbed []sql.StatementParameterListItem through executeAndPoll, submitStatement, executeBatch, and runOneBatchQuery.
• --param flag registered on both newQueryCmd and newStatementSubmitCmd.
• Help text and examples updated.

No NEXT_CHANGELOG.md entry: this is still under experimental aitools tools.

Test plan

• ./task checks clean (tidy, whitespace, links, deadcode)
• ./task lint-q clean (0 issues)
• ./task fmt clean (no changes)
• go test ./experimental/aitools/... passes
• New unit tests for parser: typed, untyped, value with embedded =/:, decimal types with parens, empty value, whitespace trimming, error cases (no =, empty name, duplicates)
• New mock-based tests confirming Parameters reaches ExecuteStatement for executeAndPoll, submitStatement, and executeBatch
• Manual smoke test against a real warehouse (databricks experimental aitools tools query --param name=alice "SELECT :name")

[github-actions]

Waiting for approval

Based on git history, these people are best suited to review:

• @pietern -- recent work in experimental/aitools/cmd/

Eligible reviewers: @MarioCadenas, @Shridhad, @arsenyinfo, @atilafassina, @calvarjorge, @ditadi, @fjakobs, @igrekun, @jamesbroadhead, @keugenek, @lennartkats-db, @pffigueiredo, @pkosiec

_{Suggestions based on git history. See OWNERS for ownership rules.}